A lens hood helps improve photo quality by cutting off excess light from entering the lens of a camera. It minimizes lens flare when photos are taken in bright light and when a subject is back lit.
Some manufacturers include a lens hood when you buy a camera, or they can be ordered separately. You can also purchase generic lens hoods made by third-parties.
Digital camera lens hoods come in a variety of shapes, sizes and material: metal, plastic and rubber. Rubber lens hoods are usually collapsible and some extend so they can be used with a wide range of focal lengths. Collapsible hoods require less space and are easy to carry, however metal hoods offer better protection.
A lens hood can block all or part of the in-camera flash or autofocus assist lamp. If so, the hood may need to be detached otherwise shadows can appear in photos. Photo may also be underexposed or improperly focused.
When using a lens hood, check the LCD to make sure it will not been seen in a photo as it will cause a vignetting effect, where the edges of a photo are dark. If this is the case, remove or adjust the lens hood. When visible in wide angle shots, zoom in slightly until you can not see the hood.